The FLYTRAP 48" Acrobat/ Uber cheap Combat Wing
Thanks for dropping in. I'm so excited about this wing that I have to share it. It's been like 7 years now since the Revert, swifter and KF48 Kline Fogleman foiled wing plans were done. It's taken this long to get it right. I wanted to make sure all the KF possibilities were tried before giving up. The KF stepped wings made from flat foam have been known to be a little "draggy" for slope applications. This had to be changed. So with a little outside of the box thinking and a bit of luck, I crossed my fingers and gave it one more shot.

And here she is! The FLYTRAP. Apply named because once you fly it, it'll suck you in. I'm calling this airfoil the KFH (Kline Fogleman Hybrid). This should help bring the concept into a new light at least for anyone wanting to build an uber cheap, fully acrobatic slope wing. Put in some Turnigy 9g metal gear servos and you have a $20 combat machine!

This version of the Flytrap is made from FFF fan fold blue foam. Depron and dollar tree foam will work too and probably look much nicer.

The first video is of the "secret" build technique to making the foil fly.

The second video shows the very first maiden flight with winds blowing to north (normally not the ideal conditions for sloping) and yet the Flytrap is working great right outa the box, so to speak. I tried to keep the flying in close since we shot it on the iPhone.. . Wait till you see the videos of JGAF, quadshot, ray nemovia and rich gorsuch flying it. She made the rounds all day and no one wanted to put her down... But first, the costs;
How much do I need to fork out to build this ugly Betty?

And the tools? What high end equipment will it take to put one together.
-razor blade
-hot glue gun set to low
-ruler
-mono coat iron (any wing builder should already have one these)
-some packing or strapping tape
-optional blen derm for covering spar and hinging elevens (packing tape works too)
-high end marking device like those used for writing on paper.
-some kind of poker (that's what she said, ha) to make a hole in your zip tie control horn.

Special thanks to Tony65x65, Viking60, jackerbes, gold guy, gpw, JGAF, kbstingwing, vtdiy, dz1sfb, Dickeroo (Dick Kline) of course, and anyone else that I may have stole ideas from to make this wing a reality. Thanks for all your inspirations and thanks to the rest of you here on RC groups that have given so many great ideas away to those of us in need! Special thanks to Ray Nemovi and Rich Gorsuch for the handy iphone work.

Thanks Fred, goldguy, Kevin, Dick and Justin.
Justin- would you mind if I posted some footage of you flying this thing? You really had some impressive lines and brought it to life.

Ken, holy schnikies you really knocked that out fast. Thanks so much for posting the drawing. The elevons are 3" so that makes the root chord 18" and the step chord ends up at 9" and tip step chord is 4.5". I was a little concerned at first since my best results thus far where at 40% but 50 is the magic number. Any further back and the step might start to interfere with the control surfaces.

One important thing is the CG. It's perfect at 9-3/8" (9.3875) to maybe 9.5"

I cut the battery hole through both plies and hot glued a small piece of 2mm coroplast on the bottom to lower the battery. I needed the nose weight anyway so this balanced it perfectly.

Goldguy - weed wackier line on the LE would be the ticket.

Ken - Your build is so nice in white. It looks like you nailed it and I'm sure this can be tweaked a lot of directions and still work well.

I have to say so far that I have flown most of the wings that have been made to date and by far my all time favorite is the kato. The kato light is absolutely incredible even though it's built very light with small servos, they can't be easily knocked out of the sky. Their recovery is incredible and for combat, that to me is truly the most important trait. And there is no better inverted flying wing out there. Hats off to Kevin for that design and to Justin's build techniques for creating a truly acrobatic wing.

The Flytrap lfills in yet another gap with ease of build and price. It's getting really hard to get wing cores these days and this might help to keep the flying wing going strong.

So enough of my ridiculously long posts.
Ken - send me a close up of your LE. I will try to get a few more photos added today. Working off the iPad and I feel a little handicapped

Ken - send me a close up of your LE. I will try to get a few more photos added today. Working off the iPad and I feel a little handicapped

Here is what I believe you're looking for. I used the video you posted of construction as a guide to the airfoil. Beveled the inside edges of the leading edges back .5". Taped and pulled over. Used hot glue on all edges. Pressed the tips flat together. This was done to get a more consistent airfoil from left to right.

I think I know some reasons why it works so well, too. I've been gradually focusing in on what it takes to make a good flying wing DLG (not a sloper) and it is kind of parallel.

I worked up from the 24" Kferret, and went on to a PW1211 foiled wing with the same planform, then to a 36" wing with the same foil and chords -- basically just increasing the aspect ratio. The last didn't work well. The smaller lower AR ratio planes were better.

They both had more sweep, besides lower A/R. The increased sweep helped CG location -- they required proportionately less ballast, and so were lighter planes. And interestngly the KF airfoiled Kferret weighed less than the -- I don't know what to call it -- Pferret. Because the KF airfoil has a further forward CG (there is more foam forward, less aft) than a conventional airfoil. So it required less ballast, and was lighter.

Lightness is the name of the game in DLG. So I was just coming around to thinking that if I used a greater sweep angle and/or a swept TE I could eliminate ballast. I was also thinking about tip stabs, but that gets in the way of a launch peg. But I was thinking the faster moving outboard stab would produce more drag on launch and really put that corrective force where it was needed, rather than where it often is in a DLG FW -- on a short central mount.

If they were more effective at the tip, they might be reduced in size, and so reduce drag. There also seemed possibilities of asymmetric areas, foils, and orientation for DLG use, but I didn't want to go there...

Anyway, also, reduced weight, means reduction of structure needed. Reduction of structure needed for stiffness, means reduction of foil thickness as a percent of chord. Reduction of foil thickness as a percent of chord means a better glider.

So flytrap has all of the above. I just built one of GPW's A-12s which also has reduced thickess, relatively high A/R, high sweep angle, and I was really thinking about it as a glider much more than a power plane. I was thinking it would be easy to balance, low weight etc.

Fixed split drag flaps might be the one hang-up as a glider. That would go away with functional split flaps.

Anyway, not to wander too far OT, nice work Tiretrax, and even though a sloper it sure does bear out some of the things I have been thinking about lately, and gives me encouragement about possibilities for a simple good performing DLG. The complimentary or even opposite of the design direction of the Alula with its forward sweep and pod for balance.

VT - great points and thanks so much for info and ideas. The ultimate KF tests will be when modelers start hot wiring steps into traditional foils I believe. But for me, cheap and quick are the order of the day. I learned on a zagi LE sloper so foam and wings have a certain place in my nature. The draw back was always the build time of hot wired wings and it has been tough to work around it. If this wing works then imagine what can be done.

It would be great to see a DLG plan built with this hybrid KF idea using maybe 3mm depron to keep it thin.

I am totally going to make one of these out of Dollar Tree Foam Board!

The field at my kids' school is a three tiered set of sports fields, & the unobstructed breeze through is begging for a floaty glider!

What are you guys using for a spar? I'm wondering if I can get away with packing tape top/bottom of the lower panel at the spar line, or should I embed a 3/16" dowel, or both?

I'm planing on peeling the inner paper from the KF section to aid the arching of the top/bottom plates into this hybrid foil. That way I maintain the strength & durability from the outer paper layer, while ditching the weight & rigidity where it is unwanted.

Troy,
I have further updated the plan to include airfoil sections at centerline and tips, along with a better mating tip plate profile. Just wanting to know if you want it. It don't want to impose myself here.

Please impose, impose!!! This is for everyone and it's all about making something work better and better. I really appreciate the plan that you made. It's way better than the one I would have done, thanks for whipping it out, the plan that is, haha.

I am totally going to make one of these out of Dollar Tree Foam Board!

What are you guys using for a spar? I'm wondering if I can get away with packing tape top/bottom of the lower panel at the spar line, or should I embed a 3/16" dowel, or both?

~psguardian

1mm x 6mm flat spar is what I like to use. Just razor blade a slot with a quick drag of the knife, drop it, and tape it on both sides with anything. I like blen derm, but any packing tape will do. That way when the plane is junked (which can happen pretty fast in my hanger), you just pull it out and drop it in the next one.

But any spar will work. I think strapping tape top and bottom might be a good test, it's probably all ya need.

1mm x 6mm flat spar is what I like to use. Just razor blade a slot with a quick drag of the knife, drop it, and tape it on both sides with anything. I like blen derm, but any packing tape will do. That way when the plane is junked (which can happen pretty fast in my hanger), you just pull it out and drop it in the next one.

But any spar will work. I think strapping tape top and bottom might be a good test, it's probably all ya need.

Troy,

I used a 5mm CF tube on mine and just taped it in. However it leaves the back half a bit loose for my liking. I will probably have to glue it.

I haven't put mine together yet, the dowel is thin & light so I'm going to glue & embed it at the spar line. Maybe a short one in the nose area (more for weight than support), then pull packing tape tight over it top & bottom.

Nah, i'll keep it feathery for light days. I need a few good light air birds. I've been doing some ultra-low wingloading KFm birds lately that have been a blast in the 1.5 to 1.75oz/sqft range and working on the big air, finless RM-V.

Your wing method can easily be formed into precise shapes with a few internal pieces in the right places, i've used that method before with good results, basically a semi-built up foam wing. Just use two spars, one main spar at the max thickness and a stringer behind it in the appropriate location to shape the wing aft of the main spar to get the curve needed . Laying shims under the TE and lifting it up while gluing it to the top sheet will give you reflex, and gluing both sheets together ahead of the TE with shims under the top LE and wing inverted will result in a jedelsly-like section.

I'm sure a coro wing would work great on a windy day. It would probably be fast. Just stick as many spars in the flutes as needed to stiffen it up. It looked like the beetle and the mugi flew well. The crazier the better.

The KF wings need a sharp LE. That was my thinking anyway. Might be a little tough to make in coro though. Give it a shot.

Images

That looks like a fun plane to rebuild when it gets knocked down by a EPP bird foam board is for people that dont have $20-30 extra bucks for EPP I don't get it why build a plane that will only last for a short time when you can build better and fly not repair My collection of wings keeps growing and none of them are disposable like the tray that comes under a steak or maybe that plane is for slope pilots that never crash while playing around in light air there are lot's of sources for EPP out there and you could easily build this to last
Cheap is not the solution
Durability is

Just got in from lunch and testing out the hill on the General Motors Tech Center grounds for slope soaring. It's not very big, but the wind was blowing right into it. Got two decent flights on, one of which included a roll and loop. However, I am just noobing it.

That's why the Alula doesn't work around here. A wonderful flyer for sure, but can't take a joke. I think the Flytrap is the perfect 'quick and dirty build' for when you only have a half hour to build a new sloper.

I'm not a foam board fan either, but FFF and MPF works for me. I agree, EPP is the way to go for longevity and it would not be big deal to build an EPP Flytrap.

OK so I was blessed to fly Troys awesome plane on Saturday and went home and started cutting foam that night. The depron I had to use was thicker than what Troy used so not sure if I was able to get the airfoil that I need. Came out pretty flat.
Dimensions are pretty close. But what the heck I have been having fun with my sharpies . Where is a good source for flat foam?

I'm sure a coro wing would work great on a windy day. It would probably be fast. Just stick as many spars in the flutes as needed to stiffen it up. It looked like the beetle and the mugi flew well. The crazier the better.

The KF wings need a sharp LE. That was my thinking anyway. Might be a little tough to make in coro though. Give it a shot.

Will do. I'll fold the flutes lengthwise which should help to keep the LE sharp. That and going Hulk-like squishing down the flutes. Will post up some pics once I get into it.

Every vid posted so far shows Flytrap to have very nice flight characteristics

flatline dave - you a have wing that flies this good outa EPP other than a Kato? I have had every one of em from raiders to XL's to Bob Mellans killer wings, boomerangs, hundreds of custom made wings and I still have a stack off EPP and a CNC hotwire. I am all for EPP and it makes a great plane for sure, check out my Halfbad wing from NCFM just to show I am not biased against EPP. But can you build an EPP plane for under $20? Sure we all can spend more but does that mean you get more? Can you have EPP in the air from scratch to flying in an hour? Not too many EPP wings fly inverted and gain lift. Will it weigh under 10oz? This one is stiffer than a light EPP wing and you can see it in the agility. It's pretty cool to see a flat formed foam sloper hold altitude. These are pluses to me and this silly little paper plate flew all day and was traded off to 7 friendly flyers and it hit the ground no less than 50 times. Some pretty hard. She looks exactly as I brought her. No issues. So not to make a case for this wing and down your opinion, I appreciate your opinion, PRO or CON, but I would have not started this thread if I didn't think the FLYTRAP was a note-able build. She won't be for everyone. Oh, schnitz, wait a minute, we could built it outa EPP sheet. Na, she would probably be a little draggy, nevermind.

quadshot, nice video man, thanks for posting, I will link it on the first starter post. Let's get some of these built so we can knock each other 'outa the sky!

Goldguy - that is a killer looking corro wing. How'd she fly?

Steve - ya I am gonna build one with a blue wonder and 8x4 myself. It would be a great acrobatic cruiser.

Man I bounced a fanfold EPS foam wing DLG all winter long off of ice and trees, in negative temps and it's still fine. After a couple months of torture testing, small LE creases and dents came out with boiling water, a light sanding, recover the edge with lightweight packaging tape and I was good to go, like new again.

That coro wing was, well, not quite what I was looking for in a sloper. Yes it flew OK, but only in big wind with big ballast and then it became a little too heavy for our best LZ, which is full of parked vehicles, big rocks, benches, fences, poles and slow moving old people.

The only place I can really fly it is a two hour drive and two different ferry sailings away. Our best spot is just down the road 5 minutes away.

Fliteline Dave has some exceptional home brew wings and one with 'CROW', that will blow your mind. The problem here is the sites we fly at are not friendly to anything other than EPP, that and a 12V hot glue gun are mandatory.

Here's four of seven different locations we fly from.......................

GG- I sure do love seeing the PNW scenery. My home away from home the last 15 years is Prince of Wales Island, AK to the north of you. Fishing is the game so my planes stay home. They get some good blows in September. I enjoy watching the Ravens and Eagles slope.

oh yea! going to knock one out, too, with maybe just one mod from the original plan.

Interesting build/model. Was just wondering as been looking at the Flitetest :Assasin /Widow maker brochure babble. Noticed a possibly interesting bit of info:
Thick (very) airfoils work.. well ( from Fast Combat experiences, I know that they Do..)
News was /is that Slopers benefit as well.. V interesting claims.
Other bit was the "trick" of cutting off wing tips to present a flat edge to the airflow..
Eliminating entirely the need for those PITA Fin things.

Hortens are interesting.. as well... being finless
But a seriously complicated Design.. Invariably Computer generated.
Not an average exercise.. but fascinating nonetheless
Here's one: In 3 sizes http://fly2air.com/Horten-9-Mini/ind...ten-9-Mini.htm
Lotsa Wing info exists.. unfortunately it's scattered in wayyy too many locations.

Justin is right, asphalt is a bummer on belly landing the balsa Tears up foam pretty good too! Good news is, you can catch the Flytrap, it comes in pretty slow, even in wind. Or you can do what I do most of the time and try to catch it, then miss, then push stick up hard to send the nose straight into the concrete I found the trick to be, velcro in the battery and it makes for a shock absorb-er on hard landings. Battery gets ejected, plane doesn't get beat up too bad. Oh and the good news, when you trash flat foam, you razor out a section, and glue a new one it. Now she is even uglier than before! Bringing Rat Rods to the hill. Why should the car guys get all the fun!

Bare - I bet this wing would fly nice with no winglets. The KF step does some interesting things. One is that there is no tip stall issues like you have in Sipkill foils. Center fin woudl work too. Check out the KF48 from like 6 years ago. I have gone totally away from thick foils and found thin foils like the PW51 at 9% to be the ultimate for wings. Especially Swept ones. My 48" wing does amazing in all areas of combat but to be straight, there isn't much that beats the Kato for EPP wings. I suggest getting your hands on one if you like wings. It is amazing and really breaks all old theories on what should fly. Check it out.

Share your mod Steve. Always looking for improvements

PSG- ha, 5gr servos. I have a ton of em. Pretty strong too. Have been having some issues with the HXT500 servos though. They are a hit or miss for me. Went to Turnigy 9gram Metal Gears after seeing how well they worked in Justins (JGAF) Kato Light builds. No more issues.

Would anybody like to help a noob out? I'm working on my first scratch build but this looks like a great second one. Where do you guys buy your parts though? LHS or online for servos and such? Just wondering. And since some of you are pretty close you might see me with the results of my build some day. If it flies.

Would anybody like to help a noob out? I'm working on my first scratch build but this looks like a great second one. Where do you guys buy your parts though? LHS or online for servos and such? Just wondering. And since some of you are pretty close you might see me with the results of my build some day. If it flies.

4 for $18 and change. seem to work fine on my last 2 -3 planes. They are metal gear so heavier than plastic geared servos. For the money and somewhat disposable planes, they do the job. Some super cheap plastic geared ones will strip gears on one hard impact/ unscheduled landing.

Hobbyking, a sponsor here, is another resource.

I support my LHS as much as possible, however servos will be retail priced and much more than the ones above and others.

Been a fleabay shopper for years and it works for me.

TT- you asked for it! my version of the Flytrap...no wingtip fins, (central fin) rounded some corners. A tad more complex to assemble with round corners but not THAT difficult with hot glue and tape.

Images

speaker of the wind - are you gonna build a sloper or power model? As far as slopers go, this one would be a great trainer for sure. Put a motor on the back, ideally a Blue Wonder 1300kv with a 600-800 3 cell pack and she would be a slow flying winner. I used to support my local hobby shop, but cannot justify thier 10-20% over suggested retail price structuring. So, it's hobbyking for me. Turnigy 9gram metal gear servos are great and I do love the cheaper HXT 9 gram servos too. Battery? For sloper, the 700mah LiFe 2 cell RX pack is a winner! And at $2.58 each, you won't run a NiMh or NiCD pack again. If I can, I love to support Hitec. That company kicks butt and makes great product. So I try to get it on ebay or through tower. Just my 2C.

Steve O - Beautiful! I really dig the way you matched the wing tips with the center fin profile. You have an eye, my friend. My buddy Gary at our local slope, puts a center fin on everything and it looks so nice. I kept the FLYTRAP with winglets as a tribute to "wings gone by" (all the cool wings that have been made, marketed and gone under). And to cover the open hole in KF stepped airfoil, hahaha. I might have to try this design my next one if you don't mind and if I am not too darn lazy to put in the extra two minutes

1.8mm carbon fiber rod with 0.39" music wire super glued to the ends. Wrap with thread and dab super glue for strength. You can also use super glue and shrink tubing. Check the Indoor scratchbuild 3D threads for more ideas. Use a zip tie in the middle of the linkage as a control rod guide.

1.8mm carbon fiber rod with 0.39" music wire super glued to the ends. Wrap with thread and dab super glue for strength. You can also use super glue and shrink tubing. Check the Indoor scratchbuild 3D threads for more ideas. Use a zip tie in the middle of the linkage as a control rod guide.

PSG - that works too

I used the zip tie guides as well. Though my pushrods were .039" from servo to control horn. Though feeling them is a bit soft, they never see flight loads high enough to deflect them. Super simple.

In case you don't already know the "zee" bends on the pushrods allow adjusting the elevons up and down for fine tuning ...or... a crunchie cartwheel landing will let the zees receive the bending instead of the servo gears or arms snapping. Within reason.

Troy, go for it... i just modded the FT, to my tastes and I seem to be one of the central fin fan club members as well. But you are right as far as the tribute to wings. The winglets are on nearly all.

Thanks all! I'm going to place my order tomorrow to give myself time to think of anything I missed. I don't want to pay shipping again if I forget one little thing. I'm going to be able to make two planes for just about what I payed for my first one. In the mean time, it looks like I'll be busy building while I wait on the guts.

Get all geared up. Check here for servo gears of all sorts.......... http://www.himodel.com/ ..........look under radios, servos and accessories. HK use to sell gear sets for the 5 and 9 gram servos. Haven't looked for them lately, got a big stash, so they may still do.

Just started my FT and the postie showed up at my door with some Wicked Wings. What to do now? I guess it will be a double build day. It looks like the Fly will get off the board first.

I guess if I'm going to keep hanging around here I had better add a Kato to my list.

Man, you guys are REALLY making me jealous, i don't have any foam sheet left, gonna try to order some MPF this week. I cut a set of Kato templates today and i might try getting the hotwire out and hacking one out of EPS this weekend.

I tried Assassin style tips on my RM-V wing and love 'em on the slope! They're not as stable as fins, but that's a good thing since the fins felt TOO locked in for me and the V without fins, washout, or angled drag tips, while easily flyable was just a bit too squirrelly at low speed.

I bet a flytrap with Assasin style tips would be a blast, hopefully i'll find out soon.

ps,
The LHS has been my normal avenue for music wire. However, I have not yet used coiled music wire. Each time I coil the music wire I have had it all comes back to straight when released. If the coiled material remains coiled when released then that will be a problem.

It's doable, there is a video around here where a guy locks a length of wire in his power drill, feeds it through a small hole in a 1x1 wood block & tilts the the wood block. Runs the drill while sliding the block along the wire & it comes out nearly perfect.

It's genius, but I have a supply of straight stock avail so I go the lazy route.

I was about to order some coiled music wire but that stuff sounds a little harder to work with than I want for my first build. Straight it is, even if the price is a bit higher. Maybe I'll check out my local shop today. I got bad service last time though so I'm not in any hurry to buy from them again.

I was about to order some coiled music wire but that stuff sounds a little harder to work with than I want for my first build. Straight it is, even if the price is a bit higher. Maybe I'll check out my local shop today. I got bad service last time though so I'm not in any hurry to buy from them again.

PS: I don't buy coiled wire, McMaster sells straight wire in 1' and 2' lengths. That's what I use on all my planes and used to put in my Charger RC kits too. It's stainless and tempered. You can see it on the Flytrap

JGAF's rod and clevis technique is even easier and eliminates the wire altogether. It was on my Kato Light that he built for me and was super strong.

Troy wa happn? You missed my new fly trap rock! Here's pics. Looks like I got a thumbprint on the bottom pic. You get the idea.

It flew great. A bit smother than yours due to it being a bit heavier. But it did all the tricks with out any issues. Forgot to try the inverted loop but sure it would have ripped it just fine. The wind wasn't that great when it went south, but handled as well as all the Kato's did.

You nailed this design bro. Even with my mockup. Can't wait to build one to spec with the right foam, which is on its way.

Chris - what? Darn I missed ya. I'm going tomorrow from 10 on. Got another ' trap built without a spar. Doesn't seem to need it. Yours looks awesome. There will be at least two more at Dave's. Stoked it flew and it wasn't just a lucky one time hit like some of the other models I did.

Lead - thanks for dropping in. Yours looks great. I sure do like the white. How in the heck did you get it down to 6oz? That's incredible. A 48" wing at 168 grams. Holy cow! You sure won't need much lift for that. Mine is 9oz. How did you get it to balance?

Lead- was it a paper off DTF build? Gotta think so with the AUW. Two sheet? Hot glue or Foam- tac?

Have yet to start mine as flying got in the way of building and am trying my hand a hotwire wing core cutting. I totally waste foam doing this. Wrecked the first two, got a good one , then another scratch, then two more. Guess that's part of the learning curve. Part of my prob is using a jerry rigged pivot cutter.

Have had success cutting two cores first ever attempt with a WeEvil aka Weasel clone and now back to flat foam.

I reckon I can still cut straight lines and operate a hot glue gun....fingers crossed.

Yes, on mine it was paper-off DTF. I used white Gorilla glue for the large glue areas and Beacons for the smaller joints. I like hot glue, but I have trouble keeping weight down when I use it; so no hot glue on this build.

I used a 1mm x 6mm flat carbon for the spar.

Lighter builds (almost any type of craft) usually have less trouble with tail heaviness. I got lucky with my ultralight FlyTrap build; by placing all the electronics way up in the nose, it balanced with the smaller battery.

The store I bought the Foam at had black and white DTF. The foam with the black paper cover looked thinner and very wavy. The white paper covered foam was much better.